The present invention relates generally to micro-switches used in signal routing, and more particularly to direction and character of optical signals.
Signal processing is a very important part of modern technology. It is used in a wide variety of fields, such as in high-speed printing, image processing and telecommunications. Optical signals especially have become very important in recent years, since light travels at maximum speed and may not be vulnerable to interference problems that trouble electrical signals. As the definition of a composite signal increases by adding more pixels per inch, etc., it becomes necessary for signal processing equipment to handle larger and larger numbers of discrete signals in a smaller and smaller area. Equipment that switches the optical signals in these discrete channels must thus also be reduced further and further in size, a trend which has lead to the development of arrays of micro-switches.
These micro-switches can be made in a number of ways. A first type of switch uses electro-optically active material which can change its index of refraction or polarity when an electric field is applied. This type of switch can be effective, but may require the use of expensive materials, and generally require relatively high activation voltages.
Micro-machined devices of silicon (MEMS) is another approach to the fabrication of micro-switches. As the name implies, a wafer of silicon is machined by any number of processes including micro-sawing, etching, etc. to create a switching element which is free to move in some direction, either linearly or rotationally so that a signal can be directed from a first signal path into a second signal path as required. An actuator device is generally needed to move the switching element, and a problem has existed in getting each of these switching elements in an array which may include hundreds or thousands to go to precisely the same position when activated, and to return to the same position when deactivated. Since the spatial location of each incoming and outgoing beam must be precisely defined, if the switching element is not also precise in its positioning in both the activated and deactivated states, signal information may be distorted or lost.
Prior art switches include cantilever shafts which allow a switch element to be raised and lowered in and out of a beam path. These are less versatile and reliable than would be desired. It would be preferred to use switches in which the switching elements are free-standing, that is, completely unattached to the surrounding matrix material, however, these are difficult to produce and precise orientation of each of a great number of microscopic elements can be difficult to achieve.
Accordingly, there is a need for a micro-switch which can be made individually very small, and for which large multiples can be manufactured in large arrays. There is also a need for micro-switches which require only small activation voltages, are reliable, cost effective, and assume very precise positions both when activated and deactivated.
Accordingly, it is an object of the present invention to provide micro-switches which can be made very small.
Another object of the invention is to provide micro-switches which can be grouped in very large arrays.
And another object of the invention is to provide micro-switches which require only small activation voltages.
A further object of the invention is to provide micro-switches which can be very precisely positioned when in either the activated or deactivated state.
An additional object of the present invention is to provide a method of manufacture which employs the use of membranes, either primary or secondary or both, to aid in positioning the switching element or retain its position during fabrication operations.
Briefly, one preferred embodiment of the present invention is a microstructure switch having a main body, a moveable switching element, one or more membranes which connect the moveable switching element to the main body and an actuator which moves the moveable switching element from a first position to a second position. The membranes may be either or both of a primary membrane or a secondary membrane. A primary membrane may be used as a temporary membrane which serves to position the moveable switching element until it is permanently positioned by a secondary membrane, or by an actuator. At this point the temporary membrane is removed.
An advantage of the present invention is that it is very cost effective to manufacture.
Another advantage of the invention is switching elements can be made completely free-standing, but the use of a membrane as a temporary positioning device makes fabrication operations much easier.
And another advantage of the invention is low activation voltages can be used, thus allowing cheaper and less expensive power supplies to be used.
A yet further advantage of the present invention is that an actuator mechanism can be included in a secondary membrane to make an integrated mechanism.
An additional advantage is the integration of components and elements other than switch elements onto the platform through subassembly.
These and other objects and advantages of the present invention will become clear to those skilled in the art in view of the description of the best presently known mode of carrying out the invention and the industrial applicability of the preferred embodiment as described herein and as illustrated in the several figures of the drawings.